Chromium nickel steels



' higher, the higher said ratio itself.

Patented Sept. 19, 1950 CHROMIUM NICKEL STEELS Jacques Marcel Defranoux, Albertville, France,

assignor to Societc DElectro-Chimie DElectro- Metallurgie ct desAcieries Electriques DUgine, Paris, France, a corporation of France No Drawing. Application May 16, 1949, Serial N 0. 93,631. In France May 28, 1948 2 Claims.

The cold-forming and cold-working of stainless chromium-nickel steels are, though taking place mostly under comparatively satisfactory conditions, limited by the decomposition of the austenite caused by said cold-forming and coldworking. Said decomposition renders the metal hard and brittle; it is, more particularly, very difficult to subject these steels to the chequering and decorative striking operations.

Furthermore, the articles obtained by means of such steels have a color which is not very agreeable and which markedly differs from that of silver or silver-plated articles.

The present invention, which has for its main object to remedy said disadvantages consists in adding copper to the chromium-nickel steel, the proportion of so added copper being near the limit of solubility of copper in said steel but not higher than said limit.

Thus, the proportion of copper to be added is a function of the analysis of the steel. It varies according to the ratio Cr/Ni and is the It is, therefore, of about: 1% for a steel containing 18% nickel and 8% chromium, 2% for a steel containing 12% nickel and 12% chromium, 4% for asteel containing 12% nickel and 18% chromium or 8% nickel and 18% chromium; said proportions are maximum proportions.

Steels are thus obtained which are capable of being used for jewelry, decoration and domestic usesand which can be formed and worked in the cold with much less difficulty than the steels used hitherto. They are, more particularly,

comparatively easy .to roll, draw, chase, dish or chequer. ing, a color which is nearer that of silver or Furthermore, they have, after polish- 2 12% chromium, 12% nickel and 2% copper. Said steel could be rolled readily and in a perfect manner without any incident. The hot or cold. forming of said steel, more particularly its drawing, chasing or chequering could be efiected with a truly unusual easiness.

Through a cold rolling giving an elongation of 20% without any intermediary reheating a breaking strength was obtained which did not exceed -65 kg./mm.

By drawing and for a reduction of section of 40% a strength was obtained which did not exceed 88-90 kg./mm. and for a reduction of section of a strength which did not exceed -127 kg./mm.

Finally, a glazed sheet of 20/10 mm. gave on a standardized chasing test of the Erichsen type REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Country Date Great Britain Oct. 23, 1935 OTHER REFERENCES Alloys of Iron and Chromium, High Chromium, vol. 2, pages 433 and 43 1. Edited by Kinzel and Franks. Published in 1940' by the McGraw- Hill Book Co., New York.

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1. STAINLESS STEEL CONSISTING ESSENTIALLY OF ABOUT 18% NICKEL, ABOUT 8% CHROMIUM, ABOUT 1% COPPER, AND IRON. 